OCR Text |
Show 1-4) Honcata lyzed reduct ion d nitrifi ca tion method 1) Principle of NOx removal The noncatalyzed reduction denitrification method which reducing agents. such as ammonia gas, ammonia water. etc. are blown into the high temperature combustion gas removes NUx by decomposing it into harmless N2 and H20. (NOx reduction reaction mechanism) 2) Basic flow of noncatalyzed reduction denitrification system Fig. 1-23 shows the basic flow of the noncataJy zed reduction denitrification system using ammonia water. The ammonia water (25% concentration) is atomized by compressed air through a dual fluid nozz le and sprayed in the mixing chamber of incinerator. Although this example uses ammonia water as reduc ing agent the system will be the same bas ically except the supplying system of reducing agent, when liquid ammonia, urea, etc. are used. 3) Operating data Fig. 1-24 shows the re lationship between the amounL of r educing agent (ammonia gas) spray and the denitrification ratio. A ~ the amount of reducing agent spray increases, the denitrification efficiency improves. Although the efficiency varies depending on temperature conditions and shape of furnace, when the amount of ammonia spray exceeds 1.2 - 1.5 in NH 3/NOx ratio. a white smoke of ammonium chloride (N1I4CL) will be generated. NH4CL in a fume state that cannot be captured by E.S.P is formed by reacting with voluminous HCL gas in the combustion gas and an excess ammonia, reaction formula of which can be shown as below: 8 |